Primos Buck Roar

While stocking up for our annual deerhunting trip my 17 yoa Son asked if I'd buy him a Primos Buck Roar grunt call, so I did. It came with an instructional DVD which he immediately popped in the TV when we got home and started practicing. It drove my Wife nuts listening to him go "Gurrrp....gurrrrrrp......" all week. She thought we'd lost our minds and said there was no way a deer was going to come into a "duck call" like that. We got into our stands sitting about 250 yards apart. When conditions were right I could hear him calling which made me smile since I didn't expect the thing to really work. Suddenly I hear him shoot and later learn he downed a nice 8 point buck. While waiting for me to come get him he continued calling and brought in a small 7 point (which he obviously passed on since he'd already filled his buck tag). He claims both deer came crashing in and he fully believes it was the call that brought them. For once I was able to come home and tell my Wife "See? We knew what we were doing all along!"
Has anyone else used this call? Any luck?